1. Field Of The Invention
The present invention relates broadly to the application of a decorative band to the edges of panel material, and more specifically to an improved apparatus for heating the hot melt adhesive on any of various widths of such banding material and accurately applying the band to the edge of the panel precisely from the desired beginning point to the ending point.
2. Description Of The Prior Art
The raw edges of various types of panels, including sawed boards, plywood and composition materials, have heretofore been covered with strips or bands of material in order to conceal irregularities in the surface and present a durable edge with a finished, pleasing appearance. Such covering of edges is old and well known in the art, and numerous ways have been proposed for affixing the band of edging material to the board or panel. Thus, for example, metal strips, thin strips of wood or wood veneer, and plastic moldings have been affixed by conventional screw and nail type fasteners, and such strips as well as bands of a polyester resin impregnated paper sheet having a decorative appearance, have been affixed by various adhesives. Use of so-called wet adhesives for this purpose, that is, adhesives which are applied in liquid form immediately prior to application of the edge band and which require drying or curing time, is time consuming and expensive. Edge bands having a tacky material such as a rubber base adhesive, covered by a paper backing or separating strip which is removed just prior to installation, have also been proposed. They likewise have not been found completely satisfactory in that they are not readily adaptable to small scale machine application as is desirable for small job shops.
One available edge banding material which has been found particularly suitable for application to panels of various shapes and thicknesses by relatively unskilled workers is preglued with a coating of high viscosity hot-melt glue. One such edging material is described in U.S. Pat. No. 3,730,823 to Veneziale. As therein explained, the glue is heated immediately prior to application of the edge band to a temperature at which it becomes melted and, while the glue is thus melted, the banding material is pressed against the edge of the panel and becomes securely bonded thereto almost instantaneously as the glue cures.
In using such edge banding material it is, of course, necessary to heat the glue to its molten state and then almost simultaneously properly align and press the heated band into engagement with the edge of the panel. A number of machines have been proposed for applying such bands. For example, U.S. Pat. No. 3,753,832 to Veneziale describes a machine wherein the pre-glued edge band is withdrawn from a continuous roll over and in contact with a heated platen. The edge of the panel is then brought into contact with the heated band and together they are moved past associated pressure and finishing rollers which press the glued edge band surface into intimate contact with the surface of the panel edge so that the bond therebetween is completed. Another machine is described in a brochure distributed by G. Ney Inc., 3 Kennedy St., Hackensack, N.J. 07601. This particular machine is said to employ heated air to suitably raise the temperature of the adhesive as the band is withdrawn from a coil of banding material. Rubber rollers press the band into engagement with the panel edge and insure intimate contact and bonding therebetween.
The prior art devices have not proven entirely satisfactory in some cases, however. Thus, devices employing a heated platen tend to scorch the banding material and cause bubbling of the adhesive if the period of contact is for any reason excessive. They therefore require that the workpiece be moved through at a more-or-less constant rate, requiring a skilled operator. The procedure cannot be readily stopped and started nor can the speed be materially varied in applying edge banding to workpieces with edges having varying degrees of complexity. The prior art hot air edge banding devices likewise did not provide the desired degree of temperature control and consequent flexibility with regard to starting, stopping and varying the rate of feed. Difficulty was also encountered in guiding the edge band, while the glue was melted, into proper alignment with the panel edge and severing the band from the continuous roll point such that it terminated at precisely the desired point along the panel.